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Soldering Gold on Sterling Silver


#1

I often want to solder gold bezel to sterling silver. I often have
problems. For the third time now I have had the experience where the
bezel just sinks into the silver and dissapears. It’s like its there
one moment and I look away for a second (to watch where I’m putting
the torch heat) and I look back and the bezel is gone! The last one
was 22 k bezel on sterling pendant. I tried soldering (using medium
silver solder, since I’m most familiar with it) and I thought it was
good, then it fell of in the pickle. I tried again, same thing. This
time I noticed solder going to the bezel, so I tried one more time
this time heating only from below to try to get the solder to go
from the bezel down to the silver beneath. THen I got the meltdown. I
wonder if the silver solder is mixing with the gold, making a
(eutectic?) lower metling point mixture. I could have used gold
solder but it doesn’t seem to flow well for me. Maybe its the gold
solder I have.

Any suggestions welcome, sigh…


#2

Hello Todd, Try soldering yellow gold to sterling with easy silver
solder and a soft flame. Use plenty of flux, but make sure the solder
chips are touching the metal and not floating on the flux. The soft
flame is to prevent the solder from balling up too soon. It should
melt from the heat of the metal, not the heatof the torch. A sharply
pointed flame will make this all come to grief. Slow and easy does
it. When you are doing this successfully on a regular basis (and you
will be), start to use the medium solder if you like.

Have fun. Tom Arnold


#3

Todd,

Since a lot of my students work in silver, and many solder gold
bezels onto silver, I see a lot of this.

I can only surmise what your problems might be. The medium silver
solder is what I’d recommend, with a light coating of flux on all
parts, and torch heating from beneath if you can. If you’re soldering
a bezel to a pendant, which suggests being able to put it on a screen
and heating from beneath, then that would be my preferred method. I
put flat pallions of solder inside the bezel, after I’ve lightly
heated the fluxed parts until dry. With the flux now dry, the solder
bits should stay put, touching the inside wall of the bezel. I watch
for those solder pallions to melt as I’m heating. When I see the
solder flow all the way around the base of the bezel, quit heating.

(That bezel will NOT come off in the pickle!) Silver is one of the
best heat conducting metals on the planet, so realize you are going
to have to play some serious heat on the silver until the solder
flows. Keep your flame OFF that gold bezel, entirely.

By the way, what are you using for a torch? I am discovering that
many commercially available torches that are highly promoted, are
just not able to provide enough heat for adequate soldering,
especially of silver items of any size.

I’ve recently been sent 4 different torches from one torch
manufacturer to review on Orchid. After setting each of them up in my
studio, I couldn’t get ANY of them to perform even modest soldering
or melting jobs. Not enough heat output. More later on this…

Jay Whaley


#4

I think you will find it very helpful to paint on a protective medium
on the top edge of the gold bezel. I always do so. It sounds like you
are not heating the silver enough before you move to the gold/silver
joint. I also use a solder pic or exacto knife to tease the solder
along if it’s slow to go. If you do overheat the gold-to-silver ratio
and the solder crawls up the gold bezel, move the torch more to the
silver and pull the solder down with the pic or knife blade. Works
like a charm. The more you do it, the sooner it becomes second
nature.

marianne


#5

Hi Jay, that’s pretty much what I did. The only thing is that there
might have been a very small gap between the bezel and the pendent.
The gap was very small, in fact I have had no problem with medium
silver solder to fill such a very small gap (barely enough for light
to get through). But perhaps for the 22 k gold it was too much. The
torch is a Smith. It is a bit wimpy I suppose, but it was enough to
melt the gold by heating (mostly) from the bottom! I do have a larger
tip that I use for melting casting grain, but that is probably too
much!I have had this happen before with gold bezel on silver, I thnkg
the join is perfect (looks good) but it is not a solid connection. I
can ony see this after pickling.But, you are saying that silver
solder is correct to use for this, rather than gold? Is there some
issue with the silver solder not penetrating the gold.


#6
I have had the experience where the bezel just sinks into the
silver and dissapears 

This is, to me anyway, suggestive of too much heat in the wrong
place. Its common practice for some to heat from below on a metal
screen. For those it works for, fine. I generally prefer to see
exactly where the heat is going and how the metal reacts. So I heat
from the top. Imagine the heat pouring in from the opposite side of
where the join will be. In order to bring the join up to the flow
temp, the back portion has to become hotter, making it difficult to
adjust the heat down, risky. The heavier the main piece the worse it
gets. You might wind up heating for too long a period, which can
change the characteristics of the solder(if its sitting there all
balled up, shimmering and jiggling), making it even harder to flow.
At the very least you could easily burn off the flux.

In the case of a larger silver piece with a much lower mass bezel,
play the flame around the perimeter of the silver, spiraling in as
you see what the flux is doing. If the design somehow acts to block
the flame from getting in close, for instance maybe the silver bulges
out near the bezel, you can try tinning the bezel bottom. Sounds
tricky but all you do is solder the bezel to a piece of light gauge,
then lift it off, transfer it to the work after cleaning it up.

For something like this I would most likely use gold solder. Don’t
know the science of it but it seems to me gold solder is much more
eager to flow in difficult situations. I’ve found silver solder has a
bigger tendency to jump to the larger heated mass, inevitably JUST
before you think you’ve got it made. Fusteration.

A cheater trick if it helps… use some gold paste solder to get
the flow started. Its more agreeable to tight places. Then go back in
with sheet solder to finish the join if need be.

This time I noticed solder going to the bezel 

Indicative of the bezel being hotter then the base. You may have
brought the heat close in too soon.


#7

Todd,

I often want to solder gold bezel to sterling silver. I often have
problems. For the third time now I have had the experience where
the bezel just sinks into the silver and dissapears. It's like its
there one moment and I look away for a second (to watch where I'm
putting the torch heat) and I look back and the bezel is gone! 

You can use extra easy (#56) silver paste solder to attach the gold
bezel (22k) to the sterling silver. The trick is heating from below
by using a tripod and screen and not using so much heat that the
bezel will disappear.

Finalize the operation by bringing the flame to the top of the piece
to make sure all the soldered seams are tight, and solder has flowed
where you want it to flow. Keep the flame from direct contact with
the thin bezel so it will not melt; you are using conductivity of
heat to make the soldering project successful. From your description
of what has happened, you are soldering way, way too hot. Medium
silver solder usually melts at 1240 F and flows at 1350 F. The extra
easy paste solder melts at 1115 F and flows at 1205 F. Not a truly
significant difference in temperature, but enough to make a
difference when soldering one metal to the other as you are
describing.

Once the bezel is soldered, pickle to remove any of the flux that
has aided in the flow of the solder.

If you still have more soldering operations, use a solder flow
retardant to keep the solder from flowing again where you have
completed the operation of soldering the bezel to the base. You can
use yellow ochre as a flow retardant, but I love the product named
Stop-Flow. This is so very much easier to use than yellow ochre and
is so easy to remove by just soaking the object in plain water for
less than two minutes and using a toothbrush to get the residue
removed. It is one of my favorite products which I buy at The Mine
Shaft 800-654-3934 (no affiliation-just a happy shopper). Stop-flow
dries fast, retards the flow of solder where you do not want it and
removes like a dream. It is also great on patterned metal where you
have many nooks and crannies where do not want to have solder.

The Stop-flow and the extra easy paste solder is also super when you
are soldering fine silver/copper etched bi-metal. This is a winner
combination so that your pattern in copper does not sink into the
silver.


#8
suggestive of too much heat in the wrong place. 

I’ve been waiting for someone to mention one of the major factors of
this issue, but nobody exactly has. All of the things people have
said are true, too.

Specific heat is something Mr. Science (JB) can surely explain deeper
than I, but it’s a large part of this problem - the gold is getting
hotter than the silver. Silver heats up fast and cools off fast, gold
heats up slower and cools off slower - that property is specific
heat, and it’s a whole set of properties and equations and the like -
that’s Jim’s forte. So, when you apply the torch to your piece the
gold is retaining heat while the silver is shedding it…Couple
that with solder and hot silver’s propensity for dissolving gold and
you have to be very careful…


#9

Hi Todd,

It sounds like your piece is getting way too hot, not that I haven’t
seen this or have it happen to me as well. That bezel wire is thin
and this is a heat to mass issue.

One tip that has worked for me is not trying to solder everything at
once. Get enough solder in there to just tack it and then clean it
up. Often some dirty flux, or something that is inhibiting the flow
of the solder is so small you can’t see it. If the solder isn’t
flowing the way it should, then just stop, don’t force it.

I bet when you clean everything off and solder it again, it should
be fine.

One more tip. What solder are you using? If you are using gold
solder to solder your bezel, then yes, you will fry your delicate
bezel. Gold solders for lack of cadmium don’t flow as well as they
did before this carcinogen was removed. But so was the easy flow. If
you are using silver, then a small amount is needed and keep the heat
on the parent piece and off that bezel until the very end. Silver
solder is stealthy. I wants to be coaxed into flowing.

Oh, and those solder flow rates? They differ from every
manufacturer, so make sure you know which one you have. I like DH
Fell and Otto Frei for general work, color match go to Hoover and
Strong. But look at the temperatures.

Good luck!
karen


#10
Specific heat is something Mr. Science (JB) can surely explain
deeper than I, but it's a large part of this problem - the gold is
getting hotter than the silver. Silver heats up fast and cools off
fast, gold heats up slower and cools off slower - that property is
specific heat, 

Specific heat is the amount of heat required to raise temperature of
one gram of substance by one degree C. The rate at which substance
heats up and cools influenced by many other factors, some much more
important than specific heat.

and it's a whole set of properties and equations and the like -
that's Jim's forte. So, when you apply the torch to your piece the
gold is retaining heat while the silver is shedding it..... 

No such phenomena has ever been observed. When heat is applied to 2
substances, both of them, either increase or decrease in
temperature, excluding conditions of equilibrium where temperature
does not change.

Couple that with solder and hot silver's propensity for dissolving
gold and you have to be very careful... 

The only metal with propensity for dissolving gold is mercury. May be
John would clarify what exactly does he mean.

There are no particular problems in soldering gold and silver. While
there are differences in rate of heating, the causes of failure aRe:
parts are not clean, parts do not fit together, heat is not applied
correctly. All 3 can be present in different proportions and that is
why sometimes it is difficult to pinpoint one issue.

Leonid Surpin
www.studioarete.com


#11
There are no particular problems in soldering gold and silver.
All, thanks for the and ideas. 

Hi Leonid, all I know is that I’m fairly comfortable soldering silver
bezels using medium silver solder - failure rate for me is near zero.
For the four or five times I have tried the gold on silver, I’m
batting less than 50%. I thought perhaps using the 22 K gold might be
easier this time (higher melting point than the 14 k I tried before),
but no!I had another idea, to use a small propane kiln I made (like
the small ones you can buy for baking PMC) and put a stainless steel
screen over it. It has a pyrometer in it, so I could carefully
control the temp. THen just heat from below. The advantage is that
there is plenty of evenly distributed heat available.

Anyone tried this?


#12
Specific heat is the amount of heat required to raise temperature
of one gram of substance by one degree C. 

I figured this might need elaborating - it’s important to understant
the concepts, not so important to become expert on the subject.

Mr. Surpin is confusing specific heat with the definition of a BTU.
One Btu is the amount of heat needed to raise 1 gram of water by one
degree celsius. Specific heat is the ratio other substances have
relative to that, pretty much exactly the same way as specific
gravity works. Every substance has a different specific heat, and my
readings lead me to believe that nobody is exactly sure why - could
be I never read deeply enough. So, it takes one BTU to raise water
by 1C, it takes 1/2 BTU to do the same for aluminum, and 2 BTU for
mahogany (made up numbers exept the water part). A BTU is a unit of
thermal force, and has nothing to do (or little) with temperature.

On a practical level that means that if you put a quart of water and
a quart of oil on the same burner and turn it on, and after five
minutes you check the temperature, the water will be 175F and the
oil will be 165F, again not true figures, just the concept.

And that is what is happening when you solder gold and silver
together with a torch - the silver is the water and the gold is the
oil and the torch is the burner. In the case of metals, conductivity
also plays a role and the whole thing is quite complex.

No such phenomena has ever been observed. 

The reason this thread exists is because it has.

There are no particular problems in soldering gold and silver. 

One of the trickiest jobs to do is to solder gold to silver, for the
reasons many have stated here. One minute it’s fine, the next your
gold is a puddle on the surface. I’ve found that getting in and out
quickly, and also doing the job the first time (no re-flowing) is
best. For somewhat different reasons soldering little silver parts
onto brass can be equally problematic… Puddles of silver… Not
stuff you learn in books…

The real point is not the labels and definitions - it could be that
what I’m saying is not precisely specific heat or it’s a combination
of it and conductivilty. The point is that the silver and the gold
are responding differently to a common heat source, because they are
each acting according to their properties. It matters much less with
gold and platinum, for instance, because they are closer. Silver is
so conductive and has a high specific heat, and it’s quite different
than gold. And it matters…


#13
For the four or five times I have tried the gold on silver, Im
batting less than 50%. 

Here is the method which should produce 100% success.

Get your parts ready:

Scrape all joint surfaces until they are bright. make sure that all
parts fit without any gaps. anneal everything and check again. If fit
is good, pickle parts and follow with hot soapy water bath to
neutralize pickle. check the fit again. If correction required all
steps must be repeated.

Flush some solder on the bottom of the bezel. File the solder flat,
so fit remains tight, but be careful not to remove all the solder.
Repeat pickle and soap bath again.

Soldering:

handle everything with tweezes only! Dip parts in alcohol and light
it up. Flux everything. Flux should cover surfaces without beading.
If
it beads up, repeat pickle, soap bath, and alcohol again.

Place bezel on top of silver plate, turn off lights and apply heat
from underside only. Use soft reducing flame. Watch the colour of you
silver. The coloration must be even. If one part is brighter, use
different heating pattern to equalize color and thereby heat
distribution. When solder flows, stop heating immediately. You are
done!.

If this procedure seems having too many steps, it does. In normal
practice some steps may be skipped. But when troubleshooting, you
have to do each and every steps. Then by elimination, you can
determine what give you the trouble.

Leonid Surpin
www.studioarete.com


#14
Mr. Surpin is confusing specific heat with the definition of a
BTU. 

Specific heat is amount of heat requires to raise 1 gram of
substance by 1 degree of C.

There is nothing else I can add to it.

Leonid Surpin
www.studioarete.com


#15
failure rate for me is near zero. For the four or five times I have
tried the gold on silver, I'm batting less than 50%. 

One thing about Orchid that is sometimes a blessing, sometimes a
curse, sometimes both. Somebody says, “Why does my dog like to chew
on bones?” And it turns into the chemistry of saliva and the
relative strength of dentine. Maybe the dog just likes bones…

And like a foreign language, you don’t use it, you forget it. Ah, I
have fond memories of sitting in my father’s lap having him lovingly
talk aboutthe laws of thermodynamics…

So, for my own review, I went back and did some more reading about
specific heat. It’s probably not correct to say that the differences
of behavior under heat are exactly specific heat. What is entirely
correct is that part of the issue related to this topic is that gold
and silver are responding differently under the common flame, and the
branch of (materials) science that deals with that is specific heat.
Anyone who’s interested might look into: Thermal Mass/Heat Capacity,
Enthalpy of Fusion, Specific Melting Heat, Thermal Energy in general,
and perhaps heat capacity ratio for the icing on the cake. You might
want to start with thermodynamics to begin with, though…Make a
BIG bowl of popcorn…

The main reason I say all that is that we are in the kitchen. That
person over there wants to put 1.326547 grams of solidified animal
fat into the spin-formed vessel of a Duplex stainless steel with a
mixed microstructure of austenite and ferrite, putting it over a
product of the combustion of the gaseous decompostition of organic
material, loosening the bonds that hold the fat in a solid state,
thus creating a liquid state.

Me, I’m gonna put the fat in the pan and melt it. And I just won’t
go there, otherwise… You just don’t need to know that stuff to
solder two metals together… You do need to know some of what’s
happening, though…

So, yes, you could write a book about the relationships of the
thermal masses of gold and silver and the effects of conductivity
(non-conductive materials still have thermal mass/specific heat),
and the enthalpy of fusion for each and how those interact with each
other in close proximity, and throw in the propensity of the two to
dissolve into each other under heat…Me, I have jewelry to
make…

Just work carefully - there’s a place where it works, and a place
where it goes SPLAT…


#16

Hi Leonid, by “Flush some solder on the bottom of the bezel.”, would
you mean by putting the bezel on a piece of scrap metal and flowing
some solder, then lifting it off (as someone else suggested)?I
looked up specific heat of gold and silver (couldn’t find sterling,
but assume its reasonably close).

Values are Gold: 25.418 J -mol
Silver: 25.350 J -mol

It doesn’t look like they are hugely different, though of course the
conductivity is.

BTW i am an engineerand whenever I reminisce with other
engineersabout the hardest classes we ever took, it is usualy thermo
that gets the most groans.


#17
Specific heat is amount of heat requires to raise 1 gram of
substance by 1 degree of C. 

Mr Surpin is giving a limited definition of specific heat. When I
need a definition, I type in google and of course I get Mr Surpin’s
specific definition, but more generally:

The amount of heat required to raise a specified mass by one unit of
a specified temperature, usually expressed as Btu/lb/ F. or cal/g/C.


#18
by "Flush some solder on the bottom of the bezel.", would you mean
by putting the bezel on a piece of scrap metal and flowing some
solder, then lifting it off (as someone else suggested)?I looked up
specific heat of gold and silver (couldn't find sterling, but
assume its reasonably close). 

Flushing solder means to melt the solder on the side that will be
used for soldering.

To expand a bit: place some solder on the bottom of the bezel and
melt it. Later on when you assemble your piece, the bottom of the
bezel would be in contact with the plate. When you heat plate from
underside, the heat would be transferred from the plate to the bezel.
As soon as temperature will be high enough for the solder to flow, it
will flow and soldering will be accomplished. Since solder flows at
temperature less then melting point of the bezel, the bezel will
always be safe. Important to stop the moment the solder flows.

Do not worry about difference in specific heat. The actual
thermodynamics are very complex and can drive you crazy. Silver does
require more heat then gold, so heat the silver and allow it to
transfer the heat to the gold part.

In soldering 2 parts of different size, always heat the larger part
more, and in case of huge difference use indirect heat transfer to
accomplish the task.

Leonid Surpin
www.studioarete.com


#19
of course I get Mr Surpin's specific definition, but more
generally: 

The amount of heat required to raise a specified mass by one unit of
a specified temperature, usually expressed as Btu/lb/ F. or
cal/g/C…

Which means that if you put one BTU into material X for one minute,
it willheat by X degrees, and material Y will heat by Y degrees.
Science, not opinion…

hardest classes we ever took, it is usualy thermo that gets the
most groans. 

Which is why we’re not going there… Leonid said he’s never seen
it, but Leonid has also told us he’s essentially a hobbyist.

I’ve seen it, and others here have said the same. You are heating
silverwith a gold bezel (bead, wire…) on it, and when you bond
the two - it occurs upon bonding - the gold just falls and melts
into the silver like water. Fast. When you consider that 14kt gold
has a higher melting point than the sterling, it’s pretty obvious
that there’s something along the lines of specific heat going on.
Specific heat isn’t a one-liner, it’s a branch of materials science
and thermodynamics - goes way beyond what we all need to know on
this topic, me included.


#20

Todd,

Today, Thursday July 2, Jay Whaley did an hour long Blog Talk Radio
program devoted to Torches. This should now be archived and
available for download, see, blogtalkradio.com/whaleystusios

I originally felt Jay may have been a bit hard on the Little Torch,
I had even bought, but not used one. I bantered a bit with him about
it, but no matter what others presented as to how well it worked for
them, he stood his point.

I do now work at Whaley Studios and saw the torches he mentioned
arrive. he was like a kid in an unlocked Candy Shop, and laboriously
went about to change familiar torches out and replace with the new
ones. I then heard him working with a student who could not get a
gold bezel down onto a heavy silver ring. Jay took over the task,
and try as he could, was not able to get enough power and heat from
that torch, and was grumbling for the rest of the day of how
underpowered they were. He went from very happy to sadly
disappointed. He did want them to work.

That started the discussion of how many people are working with
inadequate heat because they have a very well advertised and known
torch, that fails to deliver enough heat fast enough to get the
solder to quickly flow, leading to failure.

Jay continued to search for a torch he considers fine enough for
delicate tasks and strong enough to flow solder and melt metals for
ingots. That led to the Swiss Torch he mentioned today from Otto
Frei. I also saw that one unwrap, and Jay’s amazement at the size of
some of the tips.

He apparently hooked that one up at the soldering/annealing station
over the last weekend. I was TA at the Studio on Monday, when an
experienced student came in to work. She was startled by that torch,
and asked me for help. I got it lit, but the flame was so unfamiliar
that she decided not to try to anneal her gold.

Next day, Jay’s other TA came in for Studio time and lit that torch
and was also startled. I went in and we worked together, again, we
backed off using it and called in Jay. As he did on the broadcast
today, he explained that the flame rather than being cone shaped,
was rather flat. We convinced him to put on a smaller tip. It will
take some getting used to and knowing this torch. It is top end of
the line, self igniting and impressive. A bit big for women’s hands.

Now Jay is determined to make a torch that will fill the bill, and
knowing his inventive and creative genius, I know he will. Stay
tuned for this as he has already been ordering pits and pieces, and
has begun working on it.

Today Jay put out an appeal for a very flexible black hose that was
on a Mecco Torch when he first took over this studio. If anyone has
a clue as to what it is or where it can be bought, please let Jay
know. He also had read about using Airline Tubing, and has tried it.
So far so good, but he also asked if anyone else has any experience
to share about this tubing.

As I female, with normal sized hands, excellent hand and arm
strength, and a strong grip, I have been frustrated with the torches
at the UCSD jewelry studio, and usually grip the acetylene torch way
back at the hose area, and Jay, when he sees that makes me grip the
handle properly, which causes me less control. One torch there, the
hoses, yes red and green, are so rigid and unyielding, that I get
wrist strain just trying to keep the torch in position. The hoses
want to turn it away from forward. Damn pain in the butt.

I now believe that, once again, Jay is right.
Hugs,
Terrie